/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 */

package org.apache.jmeter.gui.action;

import java.awt.Frame;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.io.IOException;
import java.util.HashSet;
import java.util.Set;

import javax.swing.JDialog;
import javax.swing.JScrollPane;

import org.apache.jmeter.gui.GuiPackage;
import org.apache.jmeter.swing.HtmlPane;
import org.apache.jmeter.util.JMeterUtils;
import org.apache.jorphan.gui.ComponentUtil;
import org.apache.jorphan.logging.LoggingManager;
import org.apache.log.Logger;

/**
 * Implements the Help menu item.
 */
public class Help implements Command {
	private static final Logger log = LoggingManager.getLoggerForClass();

	private static final Set commands = new HashSet();

	private static final String HELP_DOCS = "file:///"  // $NON-NLS-1$
		+ JMeterUtils.getJMeterHome() 
		+ "/printable_docs/usermanual/"; // $NON-NLS-1$

	private static final String HELP_PAGE = HELP_DOCS + "component_reference.html"; // $NON-NLS-1$

	public static final String HELP_FUNCTIONS = HELP_DOCS + "functions.html"; // $NON-NLS-1$

	private static JDialog helpWindow;

	private static HtmlPane helpDoc;

	private static JScrollPane scroller;

	private static String currentPage;

	static {
		commands.add(ActionNames.HELP);
		helpDoc = new HtmlPane();
		scroller = new JScrollPane(helpDoc);
		helpDoc.setEditable(false);
		try {
			helpDoc.setPage(HELP_PAGE);
			currentPage = HELP_PAGE;
		} catch (IOException err) {
			String msg = "Couldn't load help file " + err.toString();
			log.error(msg);
			currentPage = "";// Avoid NPE in resetPage() // $NON-NLS-1$
		}
	}

	/**
	 * @see org.apache.jmeter.gui.action.Command#doAction(ActionEvent)
	 */
	public void doAction(ActionEvent e) {
		if (helpWindow == null) {
			helpWindow = new JDialog(new Frame(),// independent frame to
													// allow it to be overlaid
													// by the main frame
					JMeterUtils.getResString("help"),//$NON-NLS-1$
					false);
			helpWindow.getContentPane().setLayout(new GridLayout(1, 1));
			ComponentUtil.centerComponentInWindow(helpWindow, 60);
		}
		helpWindow.getContentPane().removeAll();
		helpWindow.getContentPane().add(scroller);
		helpWindow.show();
		if (e.getSource() instanceof String[]) {
			String[] source = (String[]) e.getSource();
			resetPage(source[0]);
			helpDoc.scrollToReference(source[1]);
		} else {
			resetPage(HELP_PAGE);
			helpDoc.scrollToReference(GuiPackage.getInstance().getTreeListener().getCurrentNode().getDocAnchor());

		}
	}

	private void resetPage(String source) {
		if (!currentPage.equals(source)) {
			try {
				helpDoc.setPage(source);
				currentPage = source;
			} catch (IOException err) {
				log.error(err.toString());
				JMeterUtils.reportErrorToUser("Problem loading a help page - see log for details");
				currentPage = ""; // $NON-NLS-1$
			}
		}
	}

	/**
	 * @see org.apache.jmeter.gui.action.Command#getActionNames()
	 */
	public Set getActionNames() {
		return commands;
	}
}
